JAVA高级面试进阶训练营视频教程

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场景：

　　在做接口时，有的时候，接口入参只需要一个参数，如果将一个参数封装成一个对象很麻烦，故有了以下方式：

思路：

　　spring自带的参数解析器貌似是不具备这个能力的，所有自定义

方式方法：

　　1.定义一个注解

@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RequestSingleParam {
    String value();

    boolean required() default true;

    String defaultValue() default "";
}

　　2.定义解析器

public class RequestSingleParamHandlerMethodArgumentResolver implements HandlerMethodArgumentResolver {
    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        return parameter.hasParameterAnnotation(RequestSingleParam.class);
    }


    @Override
    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
                                  NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
        RequestSingleParam requestSingleParam = parameter.getParameterAnnotation(RequestSingleParam.class);
        HttpServletRequest request = webRequest.getNativeRequest(HttpServletRequest.class);
        BufferedReader reader = request.getReader();
        StringBuilder sb = new StringBuilder();
        char[] buf = new char[1024];
        int rd;
        while ((rd = reader.read(buf)) != -1) {
            sb.append(buf, 0, rd);
        }
        JSONObject jsonObject = JSONObject.parseObject(sb.toString());
        String value = requestSingleParam.value();
        return jsonObject.get(value);
    }

}

　　3.修改Springboot启动类(a.继承WebMvcConfigurerAdapter；b.重写addArgumentResolvers()方法)

@SpringBootApplication
@EnableWebMvc
public class SpringbootDemoApplication extends WebMvcConfigurerAdapter {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootDemoApplication.class, args);
    }

    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers){
        argumentResolvers.add(new RequestSingleParamHandlerMethodArgumentResolver());
        super.addArgumentResolvers(argumentResolvers);
    }
}

　　4.在Controller中应用　

　　调用接口方，传参如： {“name”:"张三"}，Controller中就能获取到"张三”

    @RequestMapping(value = "/test",method = RequestMethod.POST)
    public void test(@RequestSingleParam(value = "name") String name){
            System.out.println(name);
    }